A synergistically enhanced photocatalytic 2D MXene nanofibrous composite membrane for wastewater treatment

Superhydrophilic Photothermal-Responsive CuO@MXene Nanofibrous Membrane with Inherent Biofouling Resistance for Treating Complex Oily Wastewater

“…The RE ff (%) in the dye removal process with PAN, MX-PAN, and CuO@MX-PAN NFMs were 25%, 45%, and 97%, respectively. The marginal improvement in the dye removal ability of MX-PAN (45%) compared to PAN NFM (25%) may be attributed to the electrostatic interaction between the positively charged RhB dye molecules and the negatively charged MXene, as confirmed by Zeta potential analysis. ,, Additionally, a significant increase in the removal efficiency was observed in the presence of CuO@MX-PAN NFM. This superior dye removal mechanism of the resultant NFM is shown in Figure .…”

“…To further give more evidence on the photodegradation of RhB dye, it is crucial to survey the dominant active species (h + , • O 2 – , • OH) in the photocatalytic reaction . To achieve this, three scavengers were used, namely, EDTA (which quenches h + ), p -BQ (which quenches • O 2 – ), and IPA (which quenches • OH), respectively.…”

“…To further identify the dominant active species like holes (h + ), superoxide radicals ( • O 2 – ), and hydroxyl radicals ( • OH), scavengers like EDTA-2Na, p -BQ, and IPA at a concentrations of 1 mM were introduced into the RhB dye solution . The experimental procedure remained the same as those employed in the photocatalytic test, except for the introduction of scavengers before exposure to visible light.…”

Buoyancy-Assisted Fabrication of Liquid Diode: Janus Nanofibrous Membrane for Efficient Wastewater Treatment

“…To address the environmental pollution caused by oily wastewater, various technologies have been developed. Traditional methods such as gravity separation, electro-flocculation, bioremediation, demulsification, air flotation, adsorption, coagulation and flocculation, coalescence, centrifugation, and oil skimming have been used. , However, these approaches have limitations such as low separation efficiency (SE ff ), high costs of operation and maintenance, and the production of secondary pollutants, especially when treating different immiscible oil/water emulsions. ,, In this regard, polymeric membrane separation technology is considered the most effective method for separating oily wastewater, due to its inexpensiveness, high separation efficiency, and convenience of use. , Several polymeric membranes, including polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyurethane (PUR), polysulfone (PSU), and polytetrafluoroethylene (PTFE), have been developed for this purpose. , Among these, PVDF-based nanofibrous membranes play a crucial role, providing a strong and stable foundation for the membrane’s structure and performance. ,, PVDF is chosen for its remarkable chemical resistance, mechanical strength, and thermal stability, making it an ideal material for membrane applications. , The fabrication of PVDF nanofibrous membranes typically involves electrospinning (e-spinning), a technique that uses high voltage to create nanoscale fibers from a polymer solution. , This technique offers numerous advantages in the fabrication of PVDF nanofibrous membranes. It facilitates the creation of ultrafine fibers with a large surface area and enables precise control over morphology and pore structure of the fibers, enabling customization of pore size, porosity, and interconnectivity. , Additionally, the uniform distribution of fibers enhances the membranes’ mechanical strength and stability, providing opportunities for further enhancements in performance through modifications. ,, Despite the advantages of polymeric nanofibrous membrane separation technology, traditional membranes with single wettability face significant challenges in effectively separating complex oil–water emulsions. , Most superwetting membranes with singular wettability are only effective to separate specific oil or water mixtures .…”

“…Unlike traditional membranes, the Janus nanofibrous membrane acts as a liquid diode, offering a revolutionary approach to tackle the complex mixtures of w-in-o and o-in-w emulsions. , These Janus nanofibrous membranes with their distinct wetting properties have attracted significant attention for their ability to transport liquids unidirectionally, achieve high flux, and exhibit exceptional separation performance, especially in separating w-in-o and o-in-w emulsions. ,,, Achieving asymmetric wettability in Janus nanofibrous membranes can be accomplished through various means, including surface modification techniques, material selection, structural design, chemical modification, and template-assisted fabrication . For instance, incorporating metal oxides, two-dimensional (2D) or three-dimensional (3D) novel material, or growing special morphologies on the Janus nanofibrous membrane can further enhance its asymmetric wettability. ,, This leads to better performance in separating oil and water in complex emulsions. Metal oxides such as TiO 2 (titanium dioxide) or ZnO (zinc oxide) are frequently employed to impart specific properties to nanofibrous membranes.…”